A group of 9 active research investigators is requesting funds for the purchase of a Philips CM 10/PC transmission electron microscope (TEM) equipped with a cryostage/transfer device for the examination of unfixed frozen sections. All of the investigators are routinely employing electron microscopy in their research. Most members of this group are presently heavily involved in immunocytochemistry at the light microscopic level, and some are also using in situ hybridization techniques. Members of the group plan to continue their localization studies at the electron microscopic level on frozen sections. To that end they have already purchased the equipment required for cryosectioning. Obtaining the requested TEM with the cryostage will allow these studies to commence. In addition to localization work, members of the group make extensive use of standard electron microscopy in their research. The Philips TEM was selected because of its ease of use and durability with a large number of users. The microscope will be housed in the central Cell Biology Laboratory (CBL) in the Department of Anatomy and Cell Biology, and its use and maintenance will be placed under the direction of the manager of the CBL. other users of the CBL (Over 50 separate laboratories) will use the existing Philips TEM, although if beam time is available, users requiring EM localization techniques on frozen tissues will be allowed access to the Philips CM 10 TEM.